Want to help rethink the foundation of the internet? Become a PhD student at DTU Electro

Want to help rethink the foundation of the internet? Become a PhD student at DTU Electro – it only takes 20 minutes!

The internet is growing at an explosive pace - and so is its energy consumption. Yet light is still the most energy-efficient way to transmit information.
Today, data is sent around the globe as billions of light pulses every second, generated by millions of individual lasers.

We have shown that many of these lasers can be replaced by a single optical light source that emits a full rainbow spectrum of colours - and that each colour can act as its own “mini-laser”. In other words: one light source can do the job of many, making communication systems far more energy-efficient.

This is exactly the technology we are developing. And as a PhD student, you will play a key role in turning this concept into reality.

What will you be working on?
You will join an international research environment developing new ways of transmitting data - more energy-efficiently, more scalably, and with fewer active components.

Your main responsibilities include:

• Working on a project that combines photonics, modelling, chip design and hands-on experiments - in a field that is advancing rapidly.
• Contributing both independently and as part of a close-knit team where we support each other, share ideas, and lift the projects together.
• Being an active part of the group’s scientific and social community, where humour, curiosity, and good collaboration are part of everyday life.
• Collaborating with researchers, industry partners, and fellow PhD students in a team of around eight people.
• Participating in international research environments, including a planned 3–6 month research stay abroad.

How your time is typically divided:

• 2/3 research – your project, your models, your experiments.
• 1/6 teaching – e.g., exercises, supervision, or course assistance.
• 1/6 other activities – conferences, courses, group collaboration, social networks, and building strong collegial relations

The technical corner
If you already know exactly what “optical modulators operating at low SNR in spatially data-distributed links” means, you’re going to enjoy this.

If you don’t - even better, because that is exactly what you will learn here.

You must have a two-year master's degree (120 ECTS points) or a similar degree with an academic level, equivalent to a two-year master's degree, before starting the project. It may be within physics, mathematics, electrical engineering, optical communications, fibre optics, coding, or integrated photonics/nanofabrication - but whatever your background, you don’t need to know the field in depth yet. You will learn everything you need during the project.

Approval and Enrolment 
The scholarship for the PhD degree is subject to academic approval, and the candidate will be enrolled in one of the general degree programmes at DTU. For information about our enrolment requirements and the general planning of the PhD study programme, please see the Rules for the PhD proramme at DTU.

The core of your PhD project is to exploit optical frequency combs - light sources that emit a full spectrum of colours at once - and design the components that can modulate each colour’s data signal as energy-efficiently as possible.

Here are some of the concrete technical tasks you will work on:

Design and modelling

• Learning to use chip-design software to develop optical data modulators that are:
   – energy-efficient
   – as simple as possible
   – stand-alone or co-integrated with other components
   – capable of operating at low signal-to-noise ratios (low SNR)
   – flexible in terms of modulation formats and coding

Experiments and characterisation

• Testing and characterising your modulators in real communication setups, such as:
   – space-division multiplexed (SDM) fibre transmission systems
   – data-centre scenarios
   – unrepeatered data-distributed links

Modulation formats

• Discovering which modulation formats actually work best when transmitting data over… yes… a rainbow of optical colours.
• Experimenting with how to achieve maximum data capacity with minimum energy.

And don’t worry: You are not expected to understand all of this yet - but if this sounds exciting, you’re exactly the kind of candidate we’re looking for.

What do we offer?
DTU is a leading technical university globally recognized for the excellence of its research, education, innovation and scientific advice. We offer a rewarding and challenging job in an international environment. We strive for academic excellence in an environment characterized by collegial respect and academic freedom tempered by responsibility.

At DTU Electro, you get access to world-class laboratories - but also something equally important: a workplace that genuinely cares about people. 

You’ll have close supervision and mentoring from senior researchers, and a group that works together rather than in silos.

We offer:

• An open, helpful, and humorous research environment where you can ask about anything - scientific or practical.
• A culture built on respect, good manners, and a strong desire to collaborate.
• Realistic expectations, clear support, and solid scientific supervision.
• A workplace where you can conduct serious research and still enjoy yourself.
• Colleagues who help you build a strong research career - both during and after your PhD.
• DTU supports you before, during, and after parental leave, ensuring a smooth return so your research can continue to grow. As a public-sector employee in Denmark, you are entitled to paid parental leave under Danish legislation and collective agreements, providing up to 48 weeks of benefits after childbirth. The High-Speed Optical Communications group also offers extra support for young researchers, including help with maintaining research progress and preparing potential grant applications.

The employment will follow the collective agreement with the Danish Confederation of Professional Associations, which includes a seniority-based PhD salary of approx. DKK 32,000 per month. Any allowances will be agreed with the relevant union.

Apply without CV and cover letter - it only takes 20 minutes!
We use Caseflow for this recruitment, ensuring a fair and structured process that focuses only on your competences and motivation - nothing else.

That means you don’t have to submit a traditional CV or application. Instead, you simply answer a few questions about the job - and you’re already closer to an interview!

Click here to get started. (This is the only valid way to apply. Applications submitted through the DTU “Apply now” button cannot be accepted.) 

When you click, you’ll be asked to enter your email, and then a code will be sent to you.

Practical information

Salary and appointment terms
The appointment will be based on the collective agreement with the Danish Confederation of Professional Associations. The allowance will be agreed upon with the relevant union. The period of employment is 3 years.

Employment: Full-time (3-year PhD position).
Start date: 01 May 2026 or as soon as possible thereafter.
Deadline: April 2, 2026.

You may apply prior to ob­tai­ning your master's degree but cannot begin before having received it. 

Applications received after the deadline will not be considered.

All interested candidates irrespective of age, gender, disability, race, religion or ethnic background are encouraged to apply. As DTU works with research in critical technology, which is subject to special rules for security and export control, open-source background checks may be conducted on qualified candidates for the position.

Please note that applications must be submitted through Caseflow using the link above. Do NOT use the “Ansøg nu” button below, as applications submitted through that button will not be included in the assessment. 

Applications are reviewed on a rolling basis, and we therefore encourage early submission.

More info & questions?
If you have questions, you are welcome to contact Professor Leif Katsuo Oxenløwe at 45 26353928 or lkox@fotonik.dtu.dk 
For questions about the recruitment process, feel free to contact Chandra Schilling at 45 60910096 or cschi@dtu.dk

You are also very welcome to drop by for a chat - we’re always happy to offer you a cup of coffee.

For information about our enrolment requirements and the general planning of the PhD study programme, please see DTU's rules for the PhD education. You can read more about career paths at DTU here.

If you are applying from abroad, you may find useful information on working in Denmark and at DTU – Moving to Denmark. Furthermore, you have the option of joining our monthly free seminar “PhD relocation to Denmark and startup “Zoom” seminar” for all questions regarding the practical matters of moving to Denmark and working as a PhD at DTU. 

About DTU Electro
DTU Electro is one of the world’s largest research environments in photonics and electronics, with around 320 employees. We conduct research in everything from quantum photonics, nano-optics, and optical sensors to high-speed optical communications, robotics, and high-power electronics.

You will join the High-Speed Optical Communications Group (HSOC) - an international, welcoming, and collaborative team where high scientific ambition goes hand in hand with helpfulness, humour, and academic kindness. Researchers and PhD students work closely together to develop the next generation of energy-efficient and sustainable communication technologies - from optical frequency combs and new modulator designs to communication links that operate at low signal-to-noise ratios.

The group consists of around eight people and is part of a larger international network of academic and industrial partners. You will have access to advanced laboratories, state-of-the-art equipment, and colleagues who share knowledge generously, offer support, and help you move forward when something (inevitably) becomes challenging in the research process.

DTU has more than 13,500 students and 6,000 employees and is founded on a mission to develop technology for the benefit of humanity. Here, you will find academic freedom, strong communities, and the opportunity to shape your research career in a globally recognised environment.

Technology for people
DTU develops technology for people. With our international elite research and study programmes, we are helping to create a better world and to solve the global challenges formulated in the UN’s 17 Sustainable Development Goals. Hans Christian Ørsted founded DTU in 1829 with a clear mission to develop and create value using science and engineering to benefit society. That mission lives on today. DTU has 13,500 students and 6,000 employees. We work in an international atmosphere and have an inclusive, evolving, and informal working environment. DTU has campuses in all parts of Denmark and in Greenland, and we collaborate with the best universities around the world.

IMPORTANT: Please do NOT use the “Apply now” button on this page. 

DTU’s website automatically shows an “Apply now” button, but this button does not apply to this position.  To make sure your application is received, please use this Caseflow link to proceed (read more about the application process above).